It has been well known to use in a color photographic light-sensitive element a high-boiling organic solvent for dispersing oil-soluble additives. For example, with respect to dispersion of dye-releasing redox compounds or the like, Research Disclosure, Vol. 176, the December issue, No. 17643 (1978) describes a process other than a process of directly dispersing a dye-releasing redox compound by mechanical means; a process of dispersing a dye-releasing redox compound or the like by dissolving it in a high-boiling solvent as illustrated in U.S. Pat. No. 2,322,027 granted to Jelley et al. and U.S. Pat. No. 2,801,171 granted to Fierke et al. and dispersing the resulting solution in a hydrophilic colloid.
The use of such high-boiling organic solvent has long been known for introducing hydrophobic couplers capable of producing a color image by processing with a color developing agent into a silver halide emulsion layer. Useful oils for dispersing couplers include many high-boiling organic solvents in addition to those described in the aforesaid two U.S. Patents. Such high-boiling organic solvents are described in, for example, U.S. Pat. Nos. 2,533,514, 2,835,579, Japanese Patent Publication No. 23233/71, U.S. Pat. No. 3,287,134, British Pat. No. 958,441, Japanese Patent Application (OPI) No. 1031/72 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"), British Pat. No. 1,222,753, U.S. Pat. No. 3,936,303, Japanese Patent Application (OPI) Nos. 26037/76, 82078/75, U.S. Pat. Nos. 2,353,262, 2,852,383, 3,554,755, 3,676,137, 3,676,142, 3,700,454, 3,748,141, 3,837,863, German Patent Application (OLS) No. 2,538,889, Japanese Patent Application (OPI) Nos. 27921/76, 27922/76, 26035/76, 26036/76, 62632/75, Japanese Patent Publication No. 29461/74, U.S. Pat Nos. 3,936,303, 3,748,141, Japanese Patent Application (OPI) No. 1521/78, etc.
Coupler-dispersing high-boiling organic solvents for use in conventional color photographic elements, however, often provide unsatisfactory results when used for dispersing dye-releasing redox compounds or the like which are to be used in a diffusion transfer process light-sensitive element. That is, the aforesaid non-diffusible dye-releasing redox compounds, etc., have a low solubility in organic solvents due to generally larger molecular weight and higher melting point than couplers. Therefore, the use of high-boiling solvents known to be usable in conventional color photography for dispersing dye-releasing redox compounds or the like often results in insufficient solubility, formation of unstable dispersion, or low maximum image density due to poor dye-releasing activity in association with development of silver halide.